| From: | David Rowley <david(dot)rowley(at)2ndquadrant(dot)com> |
|---|---|
| To: | Justin Pryzby <pryzby(at)telsasoft(dot)com> |
| Cc: | David Wheeler <dwheeler(at)dgitsystems(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-performance(at)lists(dot)postgresql(dot)org, Cameron Redpath <credpath(at)dgitsystems(dot)com> |
| Subject: | Re: Slow planning, fast execution for particular 3-table query |
| Date: | 2019-11-07 00:15:30 |
| Message-ID: | CAKJS1f8L4QHyfj4qJsz2r6QEfcTMqx2MRPiC0PXuKZx0CjRZug@mail.gmail.com |
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| Lists: | pgsql-performance |
On Thu, 7 Nov 2019 at 11:59, Justin Pryzby <pryzby(at)telsasoft(dot)com> wrote:
>
> On Mon, Nov 04, 2019 at 03:04:45AM +0000, David Wheeler wrote:
> > Postgres version 9.5.19
> > Each of the tables has between 3-4 indexes, and all the indexes include tid as first parameter.
> But note that index definition will be prohibited since:
>
> https://www.postgresql.org/docs/9.6/release-9-6.html
> |Disallow creation of indexes on system columns, except for OID columns (David Rowley)
> |Such indexes were never considered supported, and would very possibly misbehave since the system might change the system-column fields of a tuple without updating indexes. However, previously there were no error checks to prevent them from being created.
David will have meant the user column named "tid" rather than the
system column named "ctid".
--
David Rowley http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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